from enum import auto, Enum
from random import choice, random, randint
from dungeonbattle.interfaces import Map, Tile


DEFAULT_PARAMS = {"split_chance" : .15,
        "turn_chance" : .5,
        "death_chance" : .1,
        "max_walkers" : 15,
        "width" : 100,
        "height" : 100,
        "fill" : .4}


class Directions(Enum):
    up = auto()
    down = auto()
    left = auto()
    right = auto()


class Walker:

    def __init__(self, x, y):
        self.x = x
        self.y = y
        self.dir = choice(list(Directions))

    def random_turn(self):
        self.dir = choice(list(Directions))

    def next_pos(self):
        if self.dir == Directions.up:
            return self.x, self.y + 1
        elif self.dir == Directions.down:
            return self.x, self.y - 1
        elif self.dir == Directions.right:
            return self.x + 1, self.y
        elif self.dir == Directions.left:
            return self.x - 1, self.y

    def move_in_bounds(self, width, height):
        nx, ny = self.next_pos()
        if 0 < nx < width and 0 < ny < height:
            self.x, self.y = nx, ny

    def split(self):
        child = Walker(self.x, self.y)
        child.dir = self.dir
        return child


class Generator:

    def __init__(self, params = DEFAULT_PARAMS):
        self.params = params

    def run(self):
        width, height = self.params["width"], self.params["height"]
        walkers = [Walker(width//2, height//2)]
        grid = [[Tile.WALL] * width] * height
        count = 0
        while count < self.params["fill"] * width*height:
            # because we can't add or remove walkers while looping over the pop
            # we need lists to keep track of what will be the walkers for the
            # next iteration of the main loop
            next_walker_pop = []

            for walker in walkers:
                if grid[walker.y][walker.x] == Tile.WALL:
                    count += 1
                    grid[walker.y][walker.x] = Tile.EMPTY
                if random() < self.params["turn_chance"]:
                    walker.random_turn()
                walker.move_in_bounds(width, height)
                if random() > self.params["death_chance"]:
                    next_walker_pop.append(walker)

            # we use a second loop for spliting so we're not bothered by cases 
            # like a walker not spliting because we hit the population cap even
            # though the next one would have died and freed a place
            # not a big if it happened though
            for walker in walkers:
                if len(next_walker_pop) < self.params["max_walkers"]:
                    if random() < self.params["split_chance"]:
                        next_walker_pop.append(walker.split())
            walkers = next_walker_pop

        start_x, start_y = randint(0, width), randint(0, height)
        while grid[start_y][start_x] != Tile.EMPTY:
            start_x, start_y = randint(0, width), randint(0, height)

        return Map(width, height, grid, start_x, start_y)